1. Technical Field
The present invention relates to a novel emulsion fuel that is produced by adding water to petroleum liquid fuel.
2. Background Art
Emulsion-type fuel that is produced by adding water to petroleum liquid fuel is conventionally used in order to reduce soot (dust) and NOx products in exhaust gas of the petroleum liquid fuel.
Such conventional emulsion fuel is produced by adding water (5-30%) and a small amount of surface active agents to hydrophobic liquid fossil fuel such as kerosene with mixing such that they are emulsified. At the combustion of the fuel, water contained in the emulsion fuel dramatically increases its volume (about 1,700 times as much as the original volume) when it quickly becomes steam, and the size of the fuel drops injected from a burner is made very small due to this burst of steam. As a result, a better mixture of fuel and combustion air (thus a better combustion) is achieved and the emission of soot and dust is reduced. In addition, production of NOx is also reduced during the combustion because of a lower flame temperature resulting from evaporation the latent heat of evaporation of water.
However, in the case of the conventional emulsion fuel as described above, it separates into a water layer and an oil layer in a few weeks in a storage tank or the like because the specific gravity of water and that of petroleum liquid fuel is different from each other. Thus, storage of the conventional emulsion fuel for a long period is troublesome.
In addition, as 0.08% of heat is lost against 1% of water mixing in the conventional emulsion fuel. For example, when 20% of water is mixed, about 1.6% of heat is lost. Therefore, the conventional emulsion fuel cannot be used for a boiler in which a high heat efficiency is required.